text: #ifndef ULCDST7920_H
  #define ULCDST7920_H
  
  #include "Marlin.h"
  
  #ifdef U8GLIB_ST7920
  
  //set optimization so ARDUINO optimizes this file
  #pragma GCC optimize (3)
  
  #define ST7920_CLK_PIN  LCD_PINS_D4
  #define ST7920_DAT_PIN  LCD_PINS_ENABLE
  #define ST7920_CS_PIN   LCD_PINS_RS
  
  //#define PAGE_HEIGHT 8   //128 byte framebuffer
  //#define PAGE_HEIGHT 16  //256 byte framebuffer
  #define PAGE_HEIGHT 32  //512 byte framebuffer
  
  #define LCD_PIXEL_WIDTH 128
  #define LCD_PIXEL_HEIGHT 64
  
  #include <U8glib.h>
  
  static void ST7920_SWSPI_SND_8BIT(uint8_t val)
  {
    uint8_t i;
    for( i=0; i<8; i++ )
    {
      WRITE(ST7920_CLK_PIN,0);
      delayMicroseconds(2);
      WRITE(ST7920_DAT_PIN,val&0x80); 
      val<<=1;
      WRITE(ST7920_CLK_PIN,1);
      delayMicroseconds(2);
    }
  }
  
  #define ST7920_CS()              {WRITE(ST7920_CS_PIN,1);u8g_10MicroDelay();}
  #define ST7920_NCS()             {WRITE(ST7920_CS_PIN,0);}
  #define ST7920_SET_CMD()         {ST7920_SWSPI_SND_8BIT(0xf8);u8g_10MicroDelay();}
  #define ST7920_SET_DAT()         {ST7920_SWSPI_SND_8BIT(0xfa);u8g_10MicroDelay();}
  #define ST7920_WRITE_BYTE(a)     {ST7920_SWSPI_SND_8BIT((uint8_t)((a)&0xf0u));ST7920_SWSPI_SND_8BIT((uint8_t)((a)<<4u));u8g_10MicroDelay();}
  #define ST7920_WRITE_BYTES(p,l)  {uint8_t i;for(i=0;i<l;i++){ST7920_SWSPI_SND_8BIT(*p&0xf0);ST7920_SWSPI_SND_8BIT(*p<<4);p++;}u8g_10MicroDelay();}
  
  uint8_t u8g_dev_rrd_st7920_128x64_fn(u8g_t *u8g, u8g_dev_t *dev, uint8_t msg, void *arg)
  {
    uint8_t i,y;
    switch(msg)
    {
      case U8G_DEV_MSG_INIT:
        {
          OUT_WRITE(ST7920_CS_PIN,LOW);
          OUT_WRITE(ST7920_DAT_PIN,LOW);
          OUT_WRITE(ST7920_CLK_PIN,HIGH);
  
          ST7920_CS();
          u8g_Delay(120);                 //initial delay for boot up
          ST7920_SET_CMD();
          ST7920_WRITE_BYTE(0x08);       //display off, cursor+blink off
          ST7920_WRITE_BYTE(0x01);       //clear CGRAM ram
          u8g_Delay(15);                 //delay for CGRAM clear
          ST7920_WRITE_BYTE(0x3E);       //extended mode + GDRAM active
          for(y=0;y<LCD_PIXEL_HEIGHT/2;y++)        //clear GDRAM
          {
            ST7920_WRITE_BYTE(0x80|y);   //set y
            ST7920_WRITE_BYTE(0x80);     //set x = 0
            ST7920_SET_DAT();
            for(i=0;i<2*LCD_PIXEL_WIDTH/8;i++)     //2x width clears both segments
              ST7920_WRITE_BYTE(0);
            ST7920_SET_CMD();
          }
          ST7920_WRITE_BYTE(0x0C); //display on, cursor+blink off
          ST7920_NCS();
        }
        break;
  
      case U8G_DEV_MSG_STOP:
        break;
      case U8G_DEV_MSG_PAGE_NEXT:
        {
          uint8_t *ptr;
          u8g_pb_t *pb = (u8g_pb_t *)(dev->dev_mem);
          y = pb->p.page_y0;
          ptr = (uint8_t*)pb->buf;
  
          ST7920_CS();
          for( i = 0; i < PAGE_HEIGHT; i ++ )
          {
            ST7920_SET_CMD();
            if ( y < 32 )
            {
              ST7920_WRITE_BYTE(0x80 | y);       //y
              ST7920_WRITE_BYTE(0x80);           //x=0
            }
            else
            {
              ST7920_WRITE_BYTE(0x80 | (y-32));  //y
              ST7920_WRITE_BYTE(0x80 | 8);       //x=64
            }
  
            ST7920_SET_DAT();
            ST7920_WRITE_BYTES(ptr,LCD_PIXEL_WIDTH/8); //ptr is incremented inside of macro
            y++;
          }
          ST7920_NCS();
        }
        break;
    }
  #if PAGE_HEIGHT == 8
    return u8g_dev_pb8h1_base_fn(u8g, dev, msg, arg);
  #elif PAGE_HEIGHT == 16
    return u8g_dev_pb16h1_base_fn(u8g, dev, msg, arg);
  #else
    return u8g_dev_pb32h1_base_fn(u8g, dev, msg, arg);
  #endif
  }
  
  uint8_t   u8g_dev_st7920_128x64_rrd_buf[LCD_PIXEL_WIDTH*(PAGE_HEIGHT/8)] U8G_NOCOMMON;
  u8g_pb_t  u8g_dev_st7920_128x64_rrd_pb = {{PAGE_HEIGHT,LCD_PIXEL_HEIGHT,0,0,0},LCD_PIXEL_WIDTH,u8g_dev_st7920_128x64_rrd_buf};
  u8g_dev_t u8g_dev_st7920_128x64_rrd_sw_spi = {u8g_dev_rrd_st7920_128x64_fn,&u8g_dev_st7920_128x64_rrd_pb,&u8g_com_null_fn};
  
  class U8GLIB_ST7920_128X64_RRD : public U8GLIB
  {
    public:
      U8GLIB_ST7920_128X64_RRD(uint8_t dummy) : U8GLIB(&u8g_dev_st7920_128x64_rrd_sw_spi) {}
  };
  
  
  #endif //U8GLIB_ST7920
  #endif //ULCDST7920_H
  